use rdoc ~> 3.12.3

Author: windwiny

recipes/tools/docs.rake

@@ -6,14 +6,14 @@ interpreters = RubyInstaller::BaseVersions.collect { |ver|
 }
 
 begin
-  gem 'rdoc', '~> 3.12'
+  gem 'rdoc', '~> 3.12.3'
   require 'rdoc/rdoc'
   gem 'rdoc_chm', '~> 3.1.0'
 rescue Gem::LoadError
   if Rake.application.options.show_tasks
-    puts "You need rdoc 3.12 and rdoc_chm 3.1.0 gems installed"
+    puts "You need rdoc 3.12.3 and rdoc_chm 3.1.0 gems installed"
     puts "in order to build the docs tasks."
-    puts "Try `gem install rdoc -v 3.12` and later `gem install rdoc_chm -v 3.1.0`"
+    puts "Try `gem install rdoc -v 3.12.3` and later `gem install rdoc_chm -v 3.1.0`"
     puts
   end
   interpreters = []